The purpose of this investigation is to determine the role of two possible epileptogenic factors (scarring and aluminum compounds) in the development of an epileptogenic focus. The development of an alumina cream induced epileptogenic focus will be examined in scorbutic guinea pigs, guinea pigs receiving steroids chronically and control animals. The experimental procedures reduce scar formation by preventing collagen synthesis and preventing fibroblast proliferation, respectively. Usually a large meningo- cerebral scar is produced by alumina cream application and this is thought to be one of the etiological factors in the production of epilepsy. If our hypothesis is correct then scorbutic guinea pigs and guinea pigs receiving steroids should be partly immune to epilepsy. Quantitative studies of the development of paroxysmal activity will be based on the number of epileptic spikes per unit time over days. Histological studies will include Mallory's PTAH and Holzer stains for collagen and glia. The Cox modification of the Golgi method of impregnation will be used to study the effect of the experimental procedures on neurons. The electrophysiological and histological findings will be correlated to assess the epileptogenic effect of specific morphological alterations. In a separate series of studies four aluminum compounds will be applied to the cortex of cats in acute and chronic preparations to determine the active principle of alumina cream in producing epileptiform activity.